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Les langues disponibles
Optics
Fibroptonic
Ref : 202 012
2 Experiment No. 1
Figure 6: Propagation of an infrared signal in air
ENGLISH
2.1 Equipment:
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Transmitter
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Receiver
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6, 9 or 12 V DC power supply (the optical fibre is not used)
2.2 Set-up and experiment
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Power the transmitter and the receiver (connect the red terminals to the + of the
generator and the black ones to -).
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Place the switch located beside the transmitter connector on O (on), the green LED
must come on and if we look inside the blue connector we can see a red glow in
version No. 1 which corresponds to the visible part of the emitted signal.
•
The red LED of the receiver must remain off, as it does not receive any signal.
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Place the 2 connectors facing each other (figure 6). The red LED of the receiver
must come on. The infrared signal has crossed the space between the light
transmitter and the photoreceptor. Beyond a gap of 20 mm (when powered by 12
volts) and the receiver's LED goes off.
Transmitter
2.3 Additional experiments
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Inserting a piece of paper interrupts the propagation of the signal.
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Inserting a glass slide between the light transmitter and the photoreceptor does not
stop the propagation (try with various materials).
2.4 Conclusion
A signal in the near infrared propagates through air and glass (caution, certain mediums
that are transparent in the visible range are not so in infrared at certain wavelengths,
glass for example).
Receiver
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